Ceramic Kiln

Summary

The making of ceramics is one of the oldest forms of heat-treating known to man. Clay, silica or some type of high purity alumina is shaped, dried, milled and then baked at extremely high temperatures. This high baking process changes the clay material to stone or glass. Depending on the properties that are desired from the end product will determine the material used and the method of firing the work. The rate and temperature that the piece is fired determines it outcome. Poor control in ramping the temperature could have detrimental effects on the end product especially with technical ceramics and porcelains.

Despite the caution that needs to be taken with high-end ceramics, many are making simple staple items for kilns such as furniture, bricks and other refractories. This application will go over the simple pattern control for bricks.

Keywords: kiln, tile, china, porcelain, sanitary ware, refractory,

Application Requirements

The manufacturing of refractory bricks and kiln furniture requires a two-stage temperature control process. The first stage is to completely dry out the refractories at a relatively low temperature, about 400C to 800C. This process can take anywhere from a few hours to a couple of days, depending upon the specification for the product. The second stage is to cook them at high temperature for a relatively short period of time.

The diagram illustrates an electric kiln
The kiln temperature is sensed by a high temperature type W thermocouple and controlled by a Yokogawa UP550 controller.

Depending upon the customer's requirements, there is a wide selection of profile controllers:

UP150 – Lab Ovens, Tube furnace
UP350 – Brick, Pottery, kiln furniture, refractories
UP550/UP750 – Technical ceramic parts, china, porcelain
CX1000 / 2000 – Medical & Aerospace parts. Where keeping temperature records is paramount.

The requirement is to reach the soak temperatures as quickly as possible without damaging the product in the kiln or the kiln itself. The Yokogawa UP controllers and the CX Network Control Station have features such as PV events, Wait zones based upon ramp rate deviation, guaranteed soaks and a selection between time and rate based control. These features will ensure that you temperature will not only be where you want it, but will ramp at the precise rate that you set.

Ceramic Profile